(a) Field of the Invention
This invention relates to an apparatus and method for converting rotary motion to reciprocatory motion, and to high frequency medical ventilation.
(b) Description of the Prior Art
High frequency positive-pressure ventilation is a technique for ventilating the lungs and may be used in anaesthesia and in cases of apnoea.
High frequency oscillation of air in the lungs facilitates a high rate of oxygen exchange not only by convection but also by diffusion. In particular the effective diffusion of oxygen arises from the increase in the average air velocity in the lungs.
High frequency ventilation is a comparatively recent development and is described in, for example, a Special Article in Anesthesia and Analgesia, Vol. 59, No. 8, August 1980, pages 567 to 603.
A prior technique for introducing air into the lungs at high frequency involves a valve system which periodically connects the lungs to a pressurized air supply.